rear end swap
 

I just got a 90 GMC c1500 ext longbox with the 5.7 about 130k miles It runs good but shows a couple codes (33,44) for the egr but not a big deal.

The problem with it, is the rear has a leak and the PO drove it like that and now it howls. so it needs worked on or replaced and I have no exp with rears so replaceing it with one from upullit seems my best option.

My question is how can I tell if i'm getting one thats right all my options are from newer chevys

Re: rear end swap
 

If it's howling, it could just be a pinion bearing. I'd have it checked out to make sure it's not something simple.

Re: rear end swap
 

If you do have to change it all you need to check is the distance between the spring perches and make sure the rear end you get has the right flange on the output shaft to bolt to your driveline. Pretty sure in your case that any six lug 12 bolt from a 2wd should fit. Make sure you know what your gear ratio is and you get a diff that has a ratio you can use.